Blast-furnace



ilNirED STATES JOHN M. HARTMAN, OF PHILADELPHIA, PENNSYLVANIA.

BLAST-FURNACE.

SPECIFICATION forming part of Letters Patent No. 228,528, dated June 8, 1880.

Application filed August 6, 1875).

To all whom it may concern:

Be it known that I, JOHN M. HARTMAN, of Philadelphia, Pennsylvania, have invented a new and useful Improvementin Blast-Furnaces for Producing Pig-Iron, of which the followin g is a specification.

The object of my invention is so to construct the furnace that the scafolds which now obstruct the interior may be obviated.

A scaffold is a mass of partly-fused ore, coal, and lime, which, having become pasty at or above the top of the bosh, adheres to the bosh permanently, decreasing the yield and ultimately stopping the working of the furnace.

My invention consists in the form and pro portions given to the interior lines of the furnace, and in the relative position of the mantel and water-jacket to these interior lines; also, in the carrying` up of the water-jacket to the mantel, the latter being placed a short distancebelow the pointX, known as the fusion-limit.77 The water-jacket has sight-holes through to the fire-brick.

In the drawing the figure is a vertical section through the furnace.y

The proper form of the interior lilies of the brick-work of an iron-smelting furnace has long been regarded as of great importance in its construction and essential to its successful operation.

Heretofore furnaces have been built with the wall sloping either directly from the bottom or from a point just above the tuyeres up to the bosh or widest part of the furnace. This slope is generally called the bosh, though in describing a furnace by its height and diameter of bosh it has reference to the widest diameter at the point C. At a certain distance up this incline is a point which,when the furnace is in operation, is termed the fusion-limit.7 At this point the latent heat is taken up. The stock is in a melted state for several feet below this fusion-limit, and this part of the interior of the furnace is known as the zone of fusion.77 Vhen, from any cause-such as less blast or blast at a lower temperature-there is less heat at this point the fusion-limit descends in the furnace. This lowering of the fusion-limit causes part of the melted stock to stick against the sloping side, forming a skew-back or scaffold7 upon which the descending stock lodges the sloping side at el.

until a dry wall of stock extends to the top of the furnace. The capacity of the furnace is thus reduced, and it will not make the proper quantity nor quality of iron.

To obviate this I place the sloping side G, which extends from the points d to G, above the fusion-limit, thus obviating the scaffolding and skew-backs which heretofore have formed upon the'said sloping side.

In operating furnaces as now built another difficulty is experienced with the sloping wall at a point below the fusion-limit. This wall, on account of its great thickness and the in .tense heat at this point, becomes cut away and the diameter enlarged. The heat then is not sufficiently concentrated, and irregular grades of iron are produced, instead of No. l iron.

To obviate this I build the inside wall vertical, or nearly so, from the sharp offset or curve above the pointe up to the lower end of This wall I make thin to prevent it being melted, and surround it with a water-jacket, P, up to the'mantel K. At certain distances apart holes 7c are placed in the water-jacket, through which an .examination of -the temperature of the wall of the furnace may be made, and the operations changed if necessary.

Heretofore the mantel K has been placed some distance-about seven feet-below the fusion-limit. This allows the intense heat below the fusion-limit to melt away the brick down to the level of the mantel, thus destroying the interior line of the furnace and causing irregular work. In my improved furnace this mantel is raised so that it is about three feet below the fusion-limit for a furnace of the usual capacity. This keeps the fusion-limit in the thick part of the brick-work, prevents a chill there, and consequently a scaffold from forming.

M is `the tuyere; N, the hearth. Upon this hearth, and below the tuyere, the meltedV iron collects.

The height of the fusion-limit may be ascertained in this way: First, determine the number of cubic feet of air per minute the furnace is to receive. Divide it by three for hard coal and by five for soft coal, which gives the cubic contents ofthe zone of fusion. Divide the latter in feet by the sectional area of the zone of IOO fusion in feet, and the result is the height of the fusion-limit above the centerof the tuyeres.

Practically the limit of the zone of fusion may be ascertained by thrusting an iron rod down from the top of the furnace to the melting-point.

In operating` blast-furnaces it is necessary that a certain temperature should be maintained at onehalf the height of the furnace. About this point I build one or more copper bars, S, into the wall of the furnace. The inside end is flush with the interior face of the brick-work. The exterior end projects beyond the outer wall. Into the end of this bar I insert a pyrometer or other heat-gage, s. This bar, or one of a goed conducting quality, conduct-s the temperature to its exterior end with a certain relative proportion, whereby I ascertain the temperature of the furnace at this point. As the heat changes I vary the hotblast or the burden to bring the furnace back to its normal condition of working.

I claim- 1. In a blast-furnace for making pig-iron, the combination ofthe man tel K, placed near to but below the fusion-limit X, the vertical and thin wall R, and the water-jacket I?, as herein described.

2. In a blast-furnace for making` pig-iron, the combination of the vertical wall R and the sloping' side G, the said sloping side being above the limit of fusion of the furnace, to prevent the formation of scaffolds and skewbacks, as herein described.

JOHN M. HARTMAN.

Titnesses EDWD. BROWN. J oHN F. GRANT. 

